This is the meaning of the phrase "2 heads are better than 1". 2 people can accomplish more than just 1.

Let's take this example: Bill and Joe are competing against Clara in a trivia game. Bill and Joe has each other to try to figure out which animal out of this list are not poisonous; [Platypus, Gila Monster, and Angolan Python]. Clara's not familiar with the Platypus, or the Python, for that matter, and assumes Platypus is harmless. Bill isn't familiar with the Platypus or Python, but knows Gila Monster is poisonous (its saliva, see sources below), so that's not the correct answer. Joe knows the Platypus is poisonous (its ankle spurs, see sources below), so that's not the correct answer. Joe and Bill talk to each other for a bit, and think "Hmm. If the Gila Monster and Platypus are both poisonous, wouldn't this mean the Python is perhaps a constrictor (which it is, see sources below)?" Joe and Bill choose the Angolan Python, and it's correct.

As you can see, 2 people can come up with ideas better than 1 person can.